Friedrich Heusler, a naturalist living in Basel, Switzerland, was referred to as a Rentier ("man of private means") (Neues Numern- & Adressbuch der Stadt Basel, 1862). He became an "ordinary member" of the Basel Naturforschendenen Gesellschaft in 1817. His "sizeable" mineral collection (2,500 to 3,000 specimens in five cases) was bequeathed to the Natural History Museum of the Verhandlung der Naturforschenden Gesellschaft in Basel, Switzerland, in 1862. It contained many fine specimens arrayed in five glass cases, greatly improving the museum's holdings. Among many other items, it contained "a handsome suite of pyrargyrite specimens, especially from St. Andreasberg in the Harz." He also left the sum of 100,000 francs to the University of Basel, the interest to be used to benefit disabled professors and teachers, as well as their widows and orphans.